1. Field of the Invention
The present invention relates generally to a joint for a brace for the natural slide and hinge joints in the human body. More particularly, it relates to such a joint which is slidably-coupled and which has a means for limiting the relative angular movements of the pivotally interconnected joint elements. It has specific application in contact sports in which braces are worn by athletes in order to reduce the chance of injury to the knee area and the extent of injury thereto from both forward and lateral blows and from adverse twisting. It may also be used as a load-supportive and motion-controlling joint in the rehabilitation of a damaged or diseased joint at the knee and elbow.
2. Description of the Prior Art
Slidably-coupled joints having both single and dual pivots for use in knee braces and the like have been described in the prior art. The advantages of the slidably-coupled joints are well recognized: they allow natural movement in a healthy joint and have less tendency to migrate up and down a wearer's limb and cause abrasion of the wearer's skin.
Artificial joints for knee and elbow braces having a means for limiting the relative angular movements of slidably-coupled joint elements have already been described in U.S. Pat. No. 3,779,654. In the cited patent, the joint has dual pivots which abut against edge surfaces formed in the joint elements to prevent hyperextension of the wearer's joint. The dual pivots do not move independently of each other, however. The pivot pins move in narrow slots, the widths of which are only slightly greater than the diameters of the sleeves in which the pivot pins are journalled; the position of one pivot pin determines the position of the other pivot pin. As a result, the articular motion is constrained to follow a definite path. The slots must be contoured individually to fit each wearer to avoid binding of the wearer's joint. Only a single side member in a brace incorporating such an artificial joint is practicable. Since two connected side members are required in a brace to protect a wearer's joint from torsional twisting, this artificial joint is ill-suited for use in knee braces worn by athletes participating in football, basketball, rodeo, or similar sports. Moreover, the narrow slots are exposed to allow both pivot pins to interconnect the joint elements for added strength over that afforded by a single pivot pin; such slots are highly vulnerable to jamming by clothing and other foreign objects. Consequently, the slots are undesirable for use in the applications disclosed in the cited patent which included their incorporation in artificial limbs as well as in braces designed for athletic and for orthopedic purposes.
Slidably-coupled joints of the prior art having a single pivot pin, on the other hand, allow the articular motion to be made of any combination of rotation and translation and thus can be used in a knee brace or the like having two connected side members. However, each slidably-coupled, single pivot pin joints have no means for confining the joint elements to move with respect to each other on one side of the position in which they are in longitudinal alignment. Therefore, they are incapable of preventing hyperextension of the wearer's joint. As a further consequence, these joints are not suitable for use in orthopedic devices in which a limited freedom in the relative movements of the joint elements is desirable in order to promote rapid healing and reduce joint stiffness and the atrophy of a patient's muscles. Moreover, such joints tend to be weak with the single connecting pivot pin frequently failing under the stress of longitudinal loads such as those incurred in the knee braces of athletes participating in contact sports.
Furthermore, none of the slidably-coupled joints of the prior art have been incorporated in a knee brace or the like designed to be worn by athletes which both allows freedom of motion of the large muscles of a wearer's limb as well as of the natural joint itself. In such a brace, the comfort derived from the capability of the slidably-coupled joint to follow the natural movement of the wearer's joint is at least partially annulled by the discomfort experience by the wearer, during running, due to the binding and chafing caused by the straps.